When it comes to climate change, don’t forget the microbes

A brown layer of ice algae coats the flanks of sea ice in Antarctica. These microbes thrive in sea ice ‘houses’ and are the beginning of many food webs, which branch out to feed all larger lifeforms. Melting sea ice affects ice algae, which means a diminished food web and greater risk of a starving ocean life. (Photo courtesy of Rick Cavicchioli, University of New South Wales, Australia)

Scientists are rightly focused on anticipating and preventing the major impacts that climate change will have on humans, plants and animals. But they shouldn’t forget the effect on Earth’s microbes, on which everything else depends, warns a group of 33 biologists from around the globe.

“Bacteria, viruses and other microorganisms support the existence of all higher lifeforms and will shape the response of plants and animals to climate change,” says Britt Koskella, an evolutionary biologist and assistant professor of integrative biology at UC Berkeley who collaborated on the consensus statement published today in the journal Nature Reviews Microbiology. “Microbes are themselves also profoundly affected by climate change, but are rarely the focus of climate change research, education or policy.”

While the researchers hope their statement will raise awareness about the role and vulnerability of microbes, they also are calling for the integration of microbial research into frameworks, such as climate models, for addressing climate change.

The group points out that Earth’s ‘unseen majority’ play critical functions in animal and human health, agriculture, the global food web and industry.

In our oceans, for example, where 90 percent of life is microbial, phytoplankton play the role that green plants play on land, fueling animal life from krill on up to the fish, sea birds and large mammals such as whales that feed on krill. Climate change could adversely affect the productivity of these marine microbes, threatening the stability of the food web that also supplies human food.

Climate change is altering natural and agricultural ecosystems in ways that can exacerbate zoonotic – diseases that move from animals into humans – and foodborne diseases. (UC Berkeley photo by Justin Remais)

On land, climate change is causing an increase of emissions of important greenhouse gases from microbes to the atmosphere, accelerating changes to the climate system.

Such changes could have major effects on agriculture, infectious disease and human and animal health, says another coauthor of the statement, Justin Remais, associate professor and head of the Division of Environmental Health Sciences in UC Berkeley’s School of Public Health.

“Climate change influences the viability and virulence of pathogenic microbes,” Remais says. “There is robust evidence that there will be adverse consequences of climate change on the health of domesticated animals, plants and people.”

Changes to climate are already affecting infectious diseases of domesticated animals and is intensifying the spread of certain environmental pathogens among people, such as those that cause diarrheal diseases—a major global killer of children under 5 years old.

“We know that variation in environmental conditions can affect the transmission of waterborne diseases, and can expand the number and geographic range of vectors that carry pathogens, such as mosquitos or small mammals,” Remais says. “The end result can be more intense or distant spread of disease.”

The group also argues that more resources are needed to support educators seeking to teach students about the impact of climate change on microbial life and the role of microbial life as an important determinant of climate change.

“We need to build literacy, both within the scientific community and throughout society, for our mutual dependence on microorganisms and a stable climate,” Koskella said. “That will require a commitment to greater inclusion and diversity in science education, and an emphasis on microbiology as an important lens for understanding the drivers and implications of climate change.”